1. Field of the Invention
The present invention relates to a gate valve and a semiconductor manufacturing apparatus, and more particularly, to a gate valve that seals an opening through which a substrate is carried into and out of a processing device, and a semiconductor manufacturing apparatus including the gate valve.
2. Description of the Related Art
Plasma technology is broadly used in many semiconductor devices such as integrated circuits, liquid crystal displays, solar batteries, and so on. The plasma technology is used in, for example, a coating or etching process performed on a thin film during a semiconductor manufacturing procedure. However, a high level plasma processing technology such as an ultra fine processing technology is required to manufacture a product having a higher performance and functionality. A microwave plasma processing device using plasma in a microwave band is one particular example.
When plasma processing is performed, space for the plasma processing is maintained at a high temperature in a vacuum. A transfer chamber used for carrying a substrate is separated from a plasma processing chamber by a gate valve. An O-ring included in the gate valve is easy to deteriorate in a plasma atmosphere and in general, O-rings cannot maintain plasma resistance and sealability at the same time. In order to prevent defects in a processed substrate due to a generation of particles or a reduction in sealability caused by deterioration of the O-ring in the plasma atmosphere, the O-ring is regularly changed in most cases, which can cause an increase in maintenance time and a reduction in operating time.
Reference 1 (Japanese Patent Publication No. 2004-141803) discloses a plasma processing device that prevents a generation of particles and a reduction in sealability caused by deterioration of the O-ring. In the plasma processing apparatus according to Reference 1, two gate valves are arranged between a reaction chamber and a transfer chamber, an O-ring made of metal meshes is provided at a side of the reaction chamber, and an O-ring made of a fluorine resin-based material is provided at a side of the transfer chamber, thereby blocking a plasma atmosphere.
Since plasma processing is performed at a high temperature, the gate valves are exposed to the high temperature. If a sealing member included in a gate valve is used under high temperature conditions or under frequently varying temperature conditions, the sealing member can deteriorate more rapidly in comparison to a case when the sealing member is used under normal room temperature conditions. Thus the deterioration can lead to particle generation and the sealing member should be changed frequently. Also, seal reliability can be reduced.
Furthermore, a sealing member having plasma resistance generally has lower durability and thus should be more frequently changed in comparison to a sealing member having sealability. Then a plasma processing device should be down or evacuated whenever the sealing member is changed. Therefore, operation efficiency is reduced.